WDA 中的Helper Class
本文截自 Web_Dynpro_for_ABAP_Tips_and_Tricks（已经上传，有兴趣的可以Google或者在我的资源中下载 http://download.csdn.net/detail/wren2004/5246372）
先看下代码对比，体会一下OO的妙处吧
向导生成的代码：
使用Helper Class后的代码:
添加helper Class 引用:
Helper Class 初始化：
完整代码：
class ZBITS_WD_CONTEXT_HELPER definition
public
create public .
*"* public components of class ZBITS_WD_CONTEXT_HELPER
*"* do not include other source files here!!!
public section.
data O_CONTEXT type ref to IF_WD_CONTEXT_NODE .
methods GET_ATTRIBUTE
importing
!PATH type STRING
exporting
value(VALUE) type DATA .
methods GET_ATTRIBUTES
importing
!PATH type STRING
exporting
!VALUES type DATA .
methods SET_ATTRIBUTE
importing
!PATH type STRING
!VALUE type DATA .
methods SET_ATTRIBUTES
importing
!PATH type STRING
!VALUES type DATA .
methods GET_STATIC_ATTRIBUTES_TABLE
importing
!PATH type STRING
!FROM type I default 1
!TO type I default 2147483647
exporting
!TABLE type ANY TABLE .
type-pools ABAP .
methods BIND_TABLE
importing
!PATH type STRING
!NEW_ITEMS type ANY TABLE
!SET_INITIAL_ELEMENTS type ABAP_BOOL default ABAP_TRUE
!INDEX type I optional .
methods IS_CHANGED_BY_CLIENT
importing
!PATH type STRING
returning
value(FLAG) type ABAP_BOOL .
methods GET_NODE
importing
!PATH type STRING
returning
value(RESULT) type ref to IF_WD_CONTEXT_NODE .
methods SET_CONTEXT
importing
!CONTEXT type ref to IF_WD_CONTEXT_NODE .
methods CONSTRUCTOR
importing
!CONTEXT type ref to IF_WD_CONTEXT_NODE optional .
methods SET_LEAD_SELECTION
importing
!PATH type STRING
!ELEMENT type ref to IF_WD_CONTEXT_ELEMENT .
methods RESET_CHANGED_BY_CLIENT
importing
!PATH type STRING .
methods SET_CHANGED_BY_CLIENT
importing
!PATH type STRING
!FLAG type ABAP_BOOL .
*"* private components of class ZBITS_WD_CONTEXT_HELPER
*"* do not include other source files here!!!
private section.
methods GET_ELEMENT_PATH
importing
!PATH type STRING
exporting
!ELPATH type STRING
!ATTRIBUTE type DATA .
methods GET_ELEMENT
importing
!PATH type STRING
returning
value(ELEMENT) type ref to IF_WD_CONTEXT_ELEMENT .
method bind_table.
*********************************************************************
data: lo_node type ref to if_wd_context_node.
*********************************************************************
" Validate necessary object initialisation
check o_context is bound.
" Get the element
lo_node = get_node( path ).
lo_node->bind_table( exporting new_items = new_items set_initial_elements = set_initial_elements index = index ).
endmethod.
method CONSTRUCTOR.
o_context = context.
endmethod.
method GET_ATTRIBUTE.
*********************************************************************
DATA: lv_elpath TYPE string,
lv_attribute TYPE string,
lo_element TYPE REF TO if_wd_context_element.
*********************************************************************
" Validate necessary object initialisation
CHECK o_context IS BOUND.
" Determine element path and attribute name
get_element_path( EXPORTING path = path IMPORTING elpath = lv_elpath attribute = lv_attribute ).
" Get the element
lo_element = get_element( lv_elpath ).
lo_element->get_attribute( EXPORTING name = lv_attribute IMPORTING value = value ).
endmethod.
method get_attributes.
*********************************************************************
data: lo_node type ref to if_wd_context_node.
*********************************************************************
" Validate necessary object initialisation
check o_context is bound.
" Get the element
lo_node = get_node( path ).
lo_node->get_static_attributes( importing static_attributes = values ).
endmethod.
method GET_NODE.
*********************************************************************
DATA: lv_path TYPE string,
lt_path TYPE TABLE OF string,
lv_index TYPE i,
lv_length TYPE i,
lo_node TYPE REF TO if_wd_context_node.
*********************************************************************
" Validate necessary object initialisation
CHECK me->o_context IS BOUND.
" Read the path into a table
SPLIT path AT '/' INTO TABLE lt_path.
" Get the path depth
DESCRIBE TABLE lt_path LINES lv_length.
" Root attributes
IF lv_length = 0.
lo_node = me->o_context.
ENDIF.
" Follow the path
lv_index = 0.
LOOP AT lt_path INTO lv_path.
lv_index = lv_index + 1.
IF lv_index = 1.
" Get first node in the path
lo_node = me->o_context->get_child_node( lv_path ).
ELSE.
" Get next node down the path
lo_node = lo_node->get_child_node( lv_path ).
ENDIF.
ENDLOOP.
result = lo_node.
endmethod.
method get_static_attributes_table.
*********************************************************************
data: lo_node type ref to if_wd_context_node.
*********************************************************************
" Validate necessary object initialisation
check o_context is bound.
" Get the element
lo_node = get_node( path ).
lo_node->get_static_attributes_table( exporting from = from to = to importing table = table ).
endmethod.
method IS_CHANGED_BY_CLIENT.
*********************************************************************
data: lo_node type ref to if_wd_context_node.
*********************************************************************
" Validate necessary object initialisation
check o_context is bound.
" Get the element
lo_node = get_node( path ).
flag = lo_node->IS_CHANGED_BY_CLIENT( ).
endmethod.
method RESET_CHANGED_BY_CLIENT.
*********************************************************************
data: lo_node type ref to if_wd_context_node.
*********************************************************************
" Validate necessary object initialisation
check o_context is bound.
" Get the element
lo_node = get_node( path ).
lo_node->RESET_CHANGED_BY_CLIENT( ).
endmethod.
method SET_ATTRIBUTE.
*********************************************************************
DATA: lv_elpath TYPE string,
lv_attribute TYPE string,
lo_element TYPE REF TO if_wd_context_element.
*********************************************************************
" Validate necessary object initialisation
CHECK o_context IS BOUND.
" Determine element path and attribute name
get_element_path( EXPORTING path = path IMPORTING elpath = lv_elpath attribute = lv_attribute ).
" Get the element
lo_element = get_element( lv_elpath ).
lo_element->set_attribute( EXPORTING name = lv_attribute value = value ).
endmethod.
method set_attributes.
*********************************************************************
data: lo_node type ref to if_wd_context_node.
*********************************************************************
" Validate necessary object initialisation
check o_context is bound.
" Get the element
lo_node = get_node( path ).
lo_node->set_static_attributes( exporting static_attributes = values ).
endmethod.
method SET_CHANGED_BY_CLIENT.
*********************************************************************
data: lo_node type ref to if_wd_context_node.
*********************************************************************
" Validate necessary object initialisation
check o_context is bound.
" Get the element
lo_node = get_node( path ).
lo_node->SET_CHANGED_BY_CLIENT( flag ).
endmethod.
method SET_CONTEXT.
o_context = context.
endmethod.
method set_lead_selection.
*********************************************************************
data: lo_node type ref to if_wd_context_node.
*********************************************************************
" Validate necessary object initialisation
check o_context is bound.
" Get the element
lo_node = get_node( path ).
lo_node->set_lead_selection( exporting element = element ).
endmethod.
method GET_ELEMENT.
*********************************************************************
DATA: lo_node TYPE REF TO if_wd_context_node.
*********************************************************************
" Validate necessary object initialisation
CHECK me->o_context IS BOUND.
lo_node = get_node( path ).
element = lo_node->get_element( ).
endmethod.
method GET_ELEMENT_PATH.
*********************************************************************
DATA: lv_path TYPE string,
lt_path TYPE TABLE OF string,
lv_index TYPE i,
lv_length TYPE i,
lv_lengm1 TYPE i.
*********************************************************************
" Read the path into a table
SPLIT path AT '/' INTO TABLE lt_path.
" Get the path depth
DESCRIBE TABLE lt_path LINES lv_length.
lv_lengm1 = lv_length - 1.
" Follow the path
lv_index = 0.
LOOP AT lt_path INTO lv_path.
lv_index = lv_index + 1.
IF lv_index < lv_length.
CONCATENATE elpath lv_path INTO elpath.
IF lv_index < lv_lengm1.
CONCATENATE elpath '/' INTO elpath.
ENDIF.
ELSE.
attribute = lv_path.
ENDIF.
ENDLOOP.
endmethod.